Best way to make a coin pile?
Model a coin (depending on how detailed you need just a short cylinder). Then use rigid body physics to drop the coins into a pile. cg cookie tutorial (archive). After you have a pile of coins then you can bake a normal map to a low poly mesh. Short description of the process on bottom of that page.

For the color, bake that too (also on that page). You would want a full render, or a Textures bake for the diffuse map.

If you are using cycles, the bake options are a little different.